Abstract Corncob dust is a byproduct from animal feed industry. Based on the major components, it has potential as an alternative carbon source for bio-ethanol production. To determine maximum glucose from corncob dust, incremental variables were tested: first, corncob to acid ratio (1:5 - 1:15 w/v), then, sulfuric acid concentrations (0.5%, 2%, 5% v/v), next, temperatures (80-120°C) and reaction time (0-5 h). The maximum glucose of 2.80 g/l with 0.24 g/l xylose were obtained from the optimum hydrolysis conditions at 1:10 corncob to acid ratio using 2% sulfuric acid under 110°C for 5 h. The activation energy for glucose and xylose production from corncob dust hydrolysis estimated using Arrhenius equation were 108.1 and 40.7 kJ/mole, respectively. Ethanol yield from fermentation of corncob dust hydrolysate by Candida shehatae was 1.39 mole-ethanol/mole-glucose, which was equivalent to 1,807 kJ/mole-substrate. Energy produced from ethanol was 16.8 times higher than that from energy consumed in the hydrolysis process. Therefore, bio-energy production from corncob dust hydrolysate was very efficient.